This invention relates to the art of packaging and it has particular relationship to determining if a package which is assumed to be intact has been undesirably opened. This invention is applicable not only to bottles and boxes such as are used in the food, beverage and pharmaceutical industries, but, also, to sealed documents which may be classified or valuable. The word "package", as used in this application, includes within its meaning not only bottles and boxes, but, also, sealed documents.
Sharpe, U.S. Pat. No. 4,398,089, is typical of the prior art. Sharpe discloses a container including a radiation shell shielded from radiation detectors by a shielding shell. Sharpe states that when the container is broken, the shielding shell is ruptured and the detector picks up the radiation actuating an alarm. This expedient involves the hazards of radioactivity. In addition, Sharpe does not describe what its radiation material is and what kind of radiation it emits. Gamma radiation would require a heavy lead shield. An alpha radiation emitter such as Pu238 also emits gamma rays. The gamma rays would be present inside and outside of the container and would require shielding.
It is an object of this invention to overcome the disadvantages of the prior art and to provide for monitoring the integrity of packages without relying on radiation material.